JP2002164286A - Method of manufacturing silicon single-crystal substrate and silicon epitaxial wafer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a silicon single-crystal substrate and a silicon epitaxial wafer, which can reduce the moisture content on the substrate or wafer to be fed into a reaction furnace, and also to suppress generation of moisture on the substrate or the wafer, in a temperature range of at least 1,000 to 1,100 deg.C. SOLUTION: In an annealing step, a silicon single-crystal substrate having CVD oxide films on its main and rear surfaces is heat treated under the temperature condition of not lower than 800 deg.C and higher than 900 deg.C, so that moisture concentration desorbed therefrom under the temperature condition is set to 0.1 ppm or less. In the next vapor phase growth step, the main surface of the silicon single-crystal substrate is vapor-phase grown to form a silicon epitaxial layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a silicon single crystal substrate and a silicon epitaxial wafer.

[0002]

2. Description of the Related Art A silicon epitaxial wafer (hereinafter simply referred to as "epitaxial wafer") has a silicon epitaxial layer (hereinafter simply referred to as "epitaxial layer") formed on a main surface of a silicon single crystal substrate (hereinafter simply referred to as "substrate"). It can be manufactured by vapor-phase growth in an atmosphere (vapor-phase growth step). A substrate used for manufacturing an epitaxial wafer is usually prepared according to the following steps. First, a silicon single crystal ingot manufactured by an FZ (floating zone) method or a CZ (Czochralski) method is sliced using a slicer or the like (slicing step). After slicing, the edge of the wafer is chamfered (chamfering step), then both sides are lapped and polished (lapping step), and further subjected to chemical etching (etching step). The wafer after the etching step (hereinafter, referred to as “chemically etched wafer”) is further mirror-polished by mechanochemical polishing (hereinafter, the wafer after the mirror-polishing is referred to as “mirror-polished wafer”) (mirror-polished step). Cleaning is performed.

When a high resistivity epitaxial layer is vapor-phase grown on the main surface of a low resistivity substrate, impurities (dopants) added in advance to the substrate are introduced into the growth atmosphere from the side and main back surfaces of the substrate. In order to reduce the auto-doping phenomenon in which the impurities are once released and the impurities are taken in the epitaxial layer during the vapor phase growth, an oxide film (hereinafter, referred to as a CVD) is formed on the main back surface of the chemical etch wafer by a chemical vapor deposition (CVD) method or the like. (Referred to as an oxide film).
-197128).

[0004] CVD on the main back surface of the chemical etch wafer
In order to form an oxide film, an inert gas such as nitrogen is used as a carrier gas, and 0.05% to 0.15% by volume of monosilane (SiH ₄ ) and 0.5% to 1.
The chemical etch wafer is heated in a temperature range of 350 ° C. to 450 ° C. in a nitrogen gas atmosphere mixed with 5% by volume of oxygen. Then, a CVD oxide film containing 3% by weight or more of OH groups is formed.

However, this CVD oxide film has a porous film quality, and moisture is adsorbed in the oxide film.
When the epitaxial layer is grown in a vapor phase, a minute oxide film is formed on the surface of the substrate on which the epitaxial layer is formed due to the influence of moisture released from the CVD oxide film, which may deteriorate the surface condition of the epitaxial wafer. So, CV
After forming a D oxide film, it has been proposed to perform a heat treatment to modify the CVD oxide film (JP-A-2000-2).
86268. Hereinafter, it is referred to as a prior application. ).

In the invention described in the above-mentioned prior application, as a heat treatment method for a CVD oxide film, for example, a general tube furnace or a lamp annealing furnace is used, and the atmosphere is an oxygen atmosphere, an oxygen-containing atmosphere, a nitrogen atmosphere, or an oxygen and nitrogen atmosphere. And a heat treatment temperature of 6
A temperature range of 50 ° C to 1200 ° C is required, preferably 70 ° C.
0 ° C to 1000 ° C. The higher the heat treatment temperature is, the shorter the processing time is, and the holding time is from 30 minutes to 180 minutes.

As a vapor phase growth apparatus used for vapor phase growth of an epitaxial layer, a vertical type (pancake type), a barrel type (cylinder type), a single-wafer type and the like have been conventionally used. Above all, a single-wafer-type vapor phase growth apparatus is usually used for manufacturing an epitaxial wafer having a diameter of 200 mm or more.
FIG. 1 shows an example of a single wafer type vapor phase growth apparatus.

The single wafer type vapor phase growth apparatus 10 shown in FIG.
Reactors 1a and 1b for performing vapor phase growth of epitaxial layers
And a load lock chamber 6a for loading the mirror wafer 55 into the apparatus 10, and a load lock chamber 6 for unloading the manufactured epitaxial wafer 57 out of the apparatus 10.
b and the wafers in the load lock chambers 6a and 6b and the reaction furnace 1.
a wafer transfer chamber 3 (hereinafter simply referred to as transfer chamber 3) provided with a handler 4 for transferring the wafer between the transfer chambers a and 1b.
Gate valves 5a, 5 forming a dividing wall separating the above-mentioned chambers
b, 5c and 5d. These gate valves 5a to
When one of the chambers 5d is opened, the above-mentioned chambers (reactors 1a, 1a) are opened.
b, the load lock chambers 6a and 6b, and the corresponding wafer transfer chamber 3) communicate with each other (therefore, the atmospheric gas moves between these two chambers), while the gate valve 5a. When any one of ~ 5d is closed, the corresponding two chambers are again partitioned from each other.

The load lock chamber 6a has, for example, a diameter of 20 mm.
One set of cassettes each containing 25 0 mm mirror-finished wafers can be stored, and a door is provided for loading or unloading the cassettes from outside the apparatus 10 into the load lock chamber 6a. . The load lock chamber 6a is normally maintained in a nitrogen atmosphere by a nitrogen purge gas introduced from the gas supply pipe 16a. However, when the specular wafer 55 placed in the cassette is loaded from outside the apparatus 10, the atmospheric gas outside the apparatus 10 (normally, the air in a clean room) flows into the load lock chamber 6 a. After the mirror wafer 55 is loaded, the atmospheric gas in the load lock chamber 6a is pushed out to the exhaust pipe 16b by the nitrogen purge gas and exhausted, and is gradually replaced with nitrogen. The load lock chamber 6b has the same configuration as the load lock chamber 6a,
Similarly to the load lock chamber 6a, a nitrogen atmosphere is usually maintained by a nitrogen purge gas introduced from the gas supply pipe 17a. The atmospheric gas in the load lock chamber 6b is pushed out to the exhaust pipe 17b and exhausted.

The transport chamber 3 also has load lock chambers 6a and 6b.
As in the above, the atmosphere is usually maintained in a nitrogen atmosphere. However, when any of the gate valves 5a, 5b, 5c, 5d is opened, the load lock chambers 6a, 6b or the reactors 1a, 1b are opened.
A part of the atmospheric gas flows into the transfer chamber 3, and after all the gate valves 5a to 5d are closed, the atmosphere is gradually replaced with nitrogen by a nitrogen purge gas. The handler 4 in the transfer chamber 3 moves the mirror wafer 5 from the cassette placed in the load lock chamber 6a.
A function of extracting the wafers 5 one by one and transporting them into the transport chamber 3 via the gate valve 5c, and a function of transporting the transported mirror surface wafer 55 to the reaction furnace 1a or 1b via the gate valve 5a or 5b. And the reactor 1a
Alternatively, the function of transferring the epitaxial wafer 57, which has been vapor-phase grown in 1b, into the transfer chamber 3 via the gate valve 5a or 5b,
To the load lock chamber 6b via the gate valve 5d.

The reactors 1a and 1b are connected to a gas supply pipe 11
Although a hydrogen atmosphere is always maintained by a hydrogen gas introduced from a and 11b, an etching gas such as hydrogen chloride (HCl) or a silicon gas such as trichlorosilane (SiHCl ₃ ) is required for performing a vapor phase growth process. A source gas, a dopant gas such as diborane (B ₂ H ₆ ) or phosphine (PH ₃ ) is mixed with hydrogen and supplied from the gas supply pipes 11 a and 11 b as a process gas. However, when the gate valves 5a and 5b are opened, a part of the atmospheric gas in the transfer chamber 3 flows into the reaction furnaces 1a and 1b. After the gate valves 5a and 5b are closed, hydrogen is gradually replaced by hydrogen gas. The process gas supplied to the reaction furnaces 1a and 1b is sent to a gas scrubber (not shown) through exhaust pipes 12a and 12b, where the exhaust gas converts HCl gas to HCl gas.
After completely removing the silicon source gas, the dopant gas, and the like, only the hydrogen gas is released into the atmosphere.

In order to carry the mirror wafer 55 into the reactors 1a and 1b during the vapor phase growth, first, the door of the load lock chamber 6a is opened, a cassette is carried into the load lock chamber 6a, and the load lock is performed. The door of the chamber 6a is closed. Next, the gate valve 5c is opened, one mirror surface wafer 55 is carried into the transfer chamber 3 by the handler 4, and the gate valve 5c is closed. Next, the gate valve 5a or 5b is opened, the mirror wafer 55 is mounted on the susceptor of the reaction furnace 1a or 1b by the handler 4, and the gate valve 5a or 5b is closed after the handler 4 returns to the transfer chamber 3. FIG. 12B shows a temperature cycle in the reactors 1a and 1b during vapor phase growth. The inside of the reactors 1a and 1b is, for example, always 80
It is set to 0 ° C or higher. After the mirror wafer 55 is loaded into the reaction furnaces 1a and 1b (t11), the mirror wafer 55 is
To remove the natural oxide film formed on the surface of
For example, the temperature is raised to 1150 ° C. (t12), and a desired time (t12)
Hold at this temperature until 13). Thereafter, the temperature is lowered to the growth temperature of the epitaxial layer (for example, 1130 ° C.) (t1).
4) The temperature is maintained until the growth is completed (t15). After completion of the vapor phase growth, the temperature is lowered to 800 ° C. (t1)
6). In order to carry out the epitaxial wafer 57 after the vapor phase growth from the vapor phase growth apparatus 10, first, the gate valve 5
a or 5b to open the handler 4a from the reactor 1a or 1b.
To carry out the epitaxial wafer 57 to the transfer chamber 3, and close the gate valve 5a or 5b. Next, the gate valve 5d is opened, the epitaxial wafer 57 is transferred from the transfer chamber 3 to the cassette in the load lock chamber 6b by the handler 4, and after the handler 4 returns to the inside of the transfer chamber 3, the gate valve 5d is closed. Next, the door of the load lock chamber 6b is opened, and the cassette is unloaded from the load lock chamber 6b. As described above, the vapor phase growth is sequentially performed on the mirror wafer 55 in the cassette loaded into the load lock chamber 6a. As a result, the epitaxial wafer 57 after the vapor phase growth is stored in the cassette in the load lock chamber 6b. Are arranged one by one. When all the vapor-phase growth on the mirror wafer of one cassette is completed, the process proceeds to the vapor-phase growth on the mirror wafer of the next cassette.

[0013]

In the vapor phase growth step, as described above, a minute oxide film is formed on the surface of a substrate on which an epitaxial layer is formed due to the influence of moisture desorbed from a CVD oxide film. In some cases, the surface condition of the epitaxial wafer may be deteriorated (it may cause surface roughness). In addition, HCl gas and silicon source gas used in the vapor phase growth process show extremely strong corrosiveness when moisture is present in the reaction furnace, and may cause metal contamination and crystal defects on epitaxial wafers. I do. Among them, metal contamination is caused by H in the presence of moisture.
As a result of corrosion of metal members of the reaction furnace, gas supply pipes, or exhaust pipes by Cl gas or silicon source gas, metals are generated by being taken into the wafer. Crystal defects are caused, for example, by the reaction of silicon raw material such as trichlorosilane with moisture in a reaction furnace to generate SiO ₂ particles, which drop on a substrate or a growing epitaxial layer. I do.

When the doors of the load lock chambers 6a and 6b are opened, the moisture contained in the air in the clean room and the atmospheric gas of the clean room when the doors of the load lock chambers 6a and 6b are opened.
6b and adheres to the inner walls of the load lock chambers 6a and 6b. This water is then supplied to the gate valve 5c,
When the gate valve 5a, 5b is opened, the reaction furnaces 1a, 1b are brought together with the atmospheric gas in the transfer chamber 3 when the gate valves 5a, 5b are opened. Brought into for that reason,
As shown in FIG. 10, the degree of surface roughness (haze level) of the epitaxial layer grown immediately after opening the doors of the load lock chambers 6a and 6b is large, and thereafter, the reactors 1a and 1b
As the amount of moisture brought in decreases, so does the surface roughness. Here, FIG. 10 is a diagram showing, for each epitaxial wafer, the haze level observed by irradiating the epitaxial layer with the roughened surface with light, and the wafer numbers shown in FIG. The numbers are assigned in the order in which the wafers are subjected to vapor phase growth.

As can be seen from FIG. 10, when the gate valves 5a to 5d are opened to transfer the wafer, the moisture in the air in the clean room is brought into the reaction chambers 1a and 1b to reduce the surface roughness of the epitaxial layer. Is causing. Therefore, several torr are required in the load lock chambers 6a and 6b.
After reducing the water content in the load lock chambers 6a and 6b by reducing the pressure to r, the insides of the load lock chambers 6a and 6b are replaced with nitrogen, and then the gate valves 5c and 5d are opened. Attempts have been made to reduce the amount of moisture brought into the chambers 1a and 1b.

However, the load lock chambers 6a, 6b
When the moisture concentration in the exhaust gas flowing through the exhaust pipe 12a or 12b is measured even after the moisture in the inside is sufficiently reduced, a concentration of about 10 ppm is often observed. The moisture is observed, for example, during the temperature rise before the epitaxial layer is grown, and does not disappear even in a temperature range of 1000 ° C. to 1100 ° C. where the surface of the epitaxial layer is likely to be rough. That is, as described above, there is a problem that the surface roughness of the epitaxial layer cannot be sufficiently reduced only by replacing the nitrogen in the load lock chambers 6a and 6b after decompression.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a method for manufacturing a silicon single crystal substrate and a silicon epitaxial wafer which can reduce the amount of water brought into a reactor. Aim. Further, the present invention relates to at least 1000 ° C to 11 ° C.
An object of the present invention is to provide a method for manufacturing a silicon single crystal substrate and a silicon epitaxial wafer that can reduce generation of moisture in a temperature region of 00 ° C.

[0018]

SUMMARY OF THE INVENTION The inventors of the present invention use process gas, moisture in a load lock chamber or a transport chamber, moisture in a reactor itself, and the production of epitaxial wafers as the cause of moisture brought into the reactor. The moisture adhering to the mirror-finished wafer to be measured was examined.

First, nitrogen forming the atmosphere of the load lock chambers 6a and 6b and the transfer chamber 3 is used as a process gas.
With respect to hydrogen forming the atmosphere of the reactors 1a and 1b,
The concentration of moisture contained in the gas supply pipes 11a, 11b, 16a, 17a was determined from the respective dew points. As a result, the water concentration in both nitrogen and hydrogen was 0.01
ppm or less, which was a level having no problem.

Next, the moisture concentrations in the atmosphere of the load lock chamber 6a and the transfer chamber 3 were determined from the respective dew points. FIG. 2 shows a state in which the door of the load lock
A state in which the moisture concentration in the load lock chamber 6a decreases with time after the door of the load lock chamber 6a is closed after exposing the inside of the load lock chamber 6a to a clean room atmosphere of 46 ° C. and a humidity of 46% for 10 minutes. During the measurement of the moisture concentration, 15 L / min of dry nitrogen was supplied into the load lock chamber 6a. As shown in FIG. 2, the water concentration that increased to about 10,000 ppm immediately after the outside air was released was about 2 ppm after 10 hours, and decreased to 1 ppm or less after 22 hours. It is known that the moisture of several ppm level in the load lock chamber 6a has substantially no problem.

FIG. 3 shows a state in which the load lock chamber 6a is moved to the transfer chamber 3.
Indicates the amount of moisture brought into the vessel. Points A, B, and C are 10 points in the load lock chamber 6a in the clean room atmosphere.
After closing the door of the load lock chamber 6a after exposing for a minute,
After purging the load lock chamber 6a with dry nitrogen for 17 hours, 5 minutes and 25 minutes, respectively, the gate valve 5c
Shows the moisture concentration when is opened. The water concentration at each point was about 40 ppm at point B, about 6 ppm at point C,
The point is about 2.5 ppm, and it can be seen that the amount of moisture brought into the transfer chamber 3 from the load lock chamber 6a decreases as the purge time of the load lock chamber 6a increases.

FIG. 4 shows the transfer lock 3 from the load lock chamber 6a.
Indicates the amount of moisture brought into the reaction furnace 1a via. At the time of this measurement, the mirror surface wafer 55 was not transported. Further, neither the silicon source gas nor the dopant gas for vapor phase growth was supplied, and only the temperature in the reactor 1a was controlled. The water concentration in the reactor 1a was measured by a semiconductor laser spectrometer installed in the exhaust pipe 12a. The method for measuring the moisture concentration by the semiconductor laser spectroscopic analyzer is a frequency modulation absorption spectroscopy in which a laser beam having a wavelength range of 1370 nm to 1389 nm is irradiated to a gas to be measured and the moisture concentration is measured by absorption. Since the water concentration in the reaction furnace 1a is substantially equal to the water concentration in the exhaust pipe 12a, the measurement result in the exhaust pipe 12a will be described below as the water concentration in the reaction furnace 1a.

FIG. 4 (a) shows how the water concentration changes in the reactor 1a. FIG. 4B shows the temperature inside the reaction furnace 1a. FIG. 4C shows an operation state of the vapor phase growth apparatus 10. Hereinafter, the vapor phase growth apparatus 10 shown in FIG.
Will be briefly described with reference to FIG. However, for the sake of simplicity, description will be made assuming that only the reaction furnace 1a is used. In FIG. 4C, “1” on the vertical axis is used.
Indicates a state in which each of the operations (one of an etch coat, a vapor phase growth, an opening operation of the gate valve 5a, and an opening operation of the door of the load lock chamber 6a) is being performed, and “0” indicates each of the operations. Indicates that no work is being performed.

First, the door of the load lock chamber 6a is opened and closed. Next, HCl gas is supplied into the reaction furnace 1a to etch the inside of the reaction furnace 1a, and further, silicon source gas is supplied to coat the susceptor disposed in the reaction furnace with silicon. Subsequently, the gate valve 5a is opened and closed.
At this time, usually, the mirror wafer 55 is carried into the reaction furnace 1a and vapor phase growth is performed, but the mirror wafer 55 is not carried. Also, no silicon source gas is supplied. After the temperature rise / fall for vapor phase growth is completed, the gate valve 5a is opened and closed again. At this time, the mirror wafer is usually unloaded from the reactor 1a. After the operation from etching in the reaction furnace 1a to opening and closing the gate valve 5a twice is repeated six times, the door of the load lock chamber 6b is opened and closed.

As is apparent from FIG. 4 (a), each time the gate valve 5a opens and closes and moisture in the load lock chamber 6a is brought into the reactor 1a via the transfer chamber 3, the reactor 1a is opened.
The water concentration in the interior rises. However, the extent of the rise is
The water concentration was about 10 ppm at the beginning when the door of the load lock chamber 6a was opened and closed, but gradually decreased to 1 ppm or less immediately before the door of the load lock chamber 6b was opened and closed.

FIG. 5 is a view similar to FIG.
5 shows a change state of the concentration of moisture brought into the reaction furnace 1a from the transfer chamber 3 through the transfer chamber 3. However, in FIG. 5, unlike the case of FIG. 4, a mirror-surface wafer having no CVD oxide film formed on the main back surface was transported. Also in this case, as in FIG. 4, the water concentration in the reaction furnace 1a gradually decreases with time.

FIG. 6 is a view similar to FIG.
5 shows a change state of the concentration of moisture brought into the reaction furnace 1a from the transfer chamber 3 through the transfer chamber 3. However, in FIG. 6, unlike the case of FIG. 5, a mirror-surface wafer having a CVD oxide film formed on the main back surface was transported. In this case, unlike the results shown in FIGS. 4 and 5, a water content of about 10 ppm in peak value is generally observed.

From the results shown in FIGS. 4, 5 and 6, it can be seen that moisture is generated from the mirror-finished wafer on which the CVD oxide film is formed. In order to explain the timing at which moisture is observed, one of the plurality of epitaxial growth steps shown in FIG. 6 is enlarged and shown in FIG. However, in FIG. 7, a silicon source gas and a dopant gas were supplied during vapor phase growth. As shown in FIG. 7, moisture is generated during etching in the reaction furnace 1a and during vapor phase growth.
In addition, 1150 ° C immediately after the start of temperature rise of the mirror wafer
Also occurs before the heat treatment in the above. That is, CV
When the mirror surface wafer having the D oxide film formed on the main back surface is heated, moisture is desorbed from the CVD oxide film.

FIG. 8 shows the concentration of water generated when a mirror-surface wafer having a CVD oxide film formed on the main back surface is heated in a hydrogen atmosphere. As a sample, a 500-nm-thick CVD oxide film was formed on the main back surface, diameter 200 mm, plane orientation (1
00), a mirror-doped wafer doped with boron having a resistivity of 0.01 Ω · cm to 0.02 Ω · cm was used. In FIG. 8, when heating of the mirror-finished wafer is started, about 200 ° C.
Except between ~ 300 ° C, the water concentration in the hydrogen atmosphere gradually increases. However, when the heating temperature exceeded about 550 ° C., the water concentration began to decrease, and at around 800 ° C., the water concentration became 0.1 ppm or less.

FIG. 9 shows the moisture concentration observed in each temperature region when the temperature of a mirror-surface wafer having a CVD oxide film formed on the main back surface is raised in a hydrogen atmosphere. The temperature rise was started from 100 ° C., and kept at the same temperature every 100 ° C. for 5 minutes. The same sample as that shown in FIG. 8 was used, but the thickness of the CVD oxide film was 300 nm.

As shown in FIG. 9, when the same temperature is maintained at 200 ° C. or more at 100 ° C. intervals for 5 minutes, the observed moisture concentrations become 0.1 ppm or less, respectively. It can be seen that the releasable water is substantially completely eliminated. Further, no water desorbed at 900 ° C. or higher was observed. This means that by heating the mirror wafer in a temperature range of 800 ° C., water can be completely eliminated from the CVD oxide film formed on the main back surface of the mirror wafer. That is, 8
When the mirror surface wafer is heated in the temperature region of 00 ° C. to desorb moisture, moisture is not desorbed from the CVD oxide film of the mirror surface wafer even if the temperature is set in the temperature range of 1000 ° C. to 1100 ° C.

As is clear from the above examination, the reactor 1
The main moisture that is brought into a
The moisture contained in the oxide film and desorbed from the CVD oxide film by heating and the atmospheric moisture contained in the atmospheric gas flowing from outside the vapor phase growth apparatus 10 with the transfer of the substrate to the reactor 1a. You can see that it is kind. Therefore, the formation of surface roughness on the surface of the epitaxial layer can be suppressed by performing vapor phase growth in the reaction furnace 1a after sufficiently removing the contained moisture and atmospheric moisture. In addition, the generation of metal contamination, crystal defects and particles on the epitaxial wafer can be suppressed.

Therefore, the method for manufacturing a silicon epitaxial wafer of the present invention is characterized in that a silicon single crystal substrate having a CVD oxide film formed on the main back surface is subjected to a heat treatment at a temperature of 800 ° C. or more and less than 900 ° C. Under the conditions, the water concentration desorbed from the silicon single crystal substrate is set to 0.
A heat treatment step of reducing the concentration to 1 ppm or less and a vapor phase growth step of forming a silicon epitaxial layer on the main surface of the silicon single crystal substrate by vapor phase growth are performed in this order.

Preferably, by reducing the pressure in the load lock chamber provided in the vapor phase growth apparatus, moisture introduced from outside the vapor phase growth apparatus is sufficiently reduced in the load lock chamber so that the moisture is not brought into the reaction furnace. To

Further, in the method of manufacturing a silicon epitaxial wafer according to the present invention, a chlorination process is performed in which a silicon single crystal substrate having a CVD oxide film formed on the main back surface is chlorinated; And a vapor phase growth step of forming a silicon epitaxial layer thereon in this order.

Further, the silicon single crystal substrate of the present invention
A silicon single crystal substrate having a CVD oxide film on a main back surface, wherein a heat treatment is performed at a temperature condition of 800 ° C. or more and less than 900 ° C., so that the concentration of water desorbed under the temperature condition is 0.1 ppm or less. It is characterized by the following.

[0037]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for manufacturing a silicon single crystal substrate and a silicon epitaxial wafer according to the present invention will be described below. The silicon single crystal substrate according to the present invention can be formed by slicing, chamfering, or the like from a silicon single crystal ingot manufactured by the FZ method or the CZ method.
Manufactured through a lapping process, an etching process, a CVD oxide film growing process, and a mirror polishing process.
A substrate for vapor phase growth on which a D oxide film has been formed.
Between the step of growing the oxide film and the step of growing the vapor phase of the epitaxial layer, a chlorine treatment or 800 treatment is performed until the concentration of water desorbed from the silicon single crystal substrate becomes 0.1 ppm or less.
It can be manufactured by performing heat treatment under a temperature condition of not less than 900 ° C. and less than 900 ° C.

By performing the heat treatment at 800 ° C. or more and less than 900 ° C. for 5 minutes or more, the concentration of water released from the CVD oxide film can be reliably reduced to 0.1 ppm or less. However, even if the heat treatment is continued for 30 minutes or more in the above temperature range, the desorption of water is no longer observed.
Less than 0 minutes is sufficient. Even if water is once attached to the CVD oxide film of the silicon single crystal substrate subjected to the heat treatment by washing or the like, the water concentration desorbed in the subsequent heat treatment at 800 ° C. or more and less than 900 ° C. is 0.1 ppm or less. Is kept.

The chlorination and heat treatment of the present invention are performed by CVD.
It may be performed between the step of growing the oxide film and the step of growing the vapor phase of the epitaxial layer. An example of a preferred embodiment will be described below.

[First Embodiment] FIG. 11 is an enlarged side sectional view of a main part showing a characteristic portion of a vapor phase growth apparatus 20 used in the first embodiment. This vapor phase growth apparatus 20
Except for the points described below, the configuration is the same as that of the vapor phase growth apparatus 10 described in Means for Solving the Problems.
The same components are denoted by the same reference numerals, and description thereof will be omitted.

The first embodiment is characterized mainly in that the heat treatment step according to the present invention is performed in a load lock chamber 26a corresponding to the load lock chamber 6a of the vapor phase growth apparatus 10. In order to preferably achieve this, the load lock chamber 26a is provided with, for example, the halogen lamps 21,.
A susceptor 28 on which the mirror wafer 55 is placed during the heat treatment step; and a quartz glass container 2 in which the susceptor 28 and the mirror wafer 55 are disposed.
7 is provided.

In the first embodiment, after the mirror wafer 55 is carried into the load lock chamber 26a, the pressure inside the load lock chamber 26a is once reduced, and then the nitrogen gas is introduced into the load lock chamber 26a. And performing the heat treatment step according to the present invention as another main feature. In order to preferably do this, the load lock chamber 26a is provided with a pressure reducing means for reducing the pressure inside the load lock chamber 26a. The decompression means includes, for example, a pump (for example, an oil diffusion type) 22 and the like, and an exhaust pipe 23.
Is connected to the inside of the load lock chamber 26a. Further, the load lock chamber 26a is
An introduction pipe 30 for introducing nitrogen gas into the inside is provided. The load lock chamber 26a is provided with an exhaust pipe 31 for exhausting nitrogen gas from the load lock chamber 26a, which is paired with the introduction pipe 30, and is introduced from the introduction pipe 30 into the load lock chamber 26a. The load lock chamber 26a is maintained in a nitrogen atmosphere by the nitrogen gas. Further, the load lock chamber 26a is
3 and valves 32 and 33 provided in the introduction pipe 30 and the exhaust pipe. In addition,
The housing 36 of the load lock chamber 26a is made of, for example, metal (for example, stainless steel) having sufficient strength and does not deform due to pressure reduction.

The number of reaction chambers provided in the vapor phase growth apparatus 20 may be, for example, only one (single) of the reaction chamber 1a, but the number of reaction chambers may be two or more (plural). Good and optional. Further, the vapor phase epitaxy apparatus 20 is provided with a handler 35 for extracting mirror wafers 55 one by one from the cassette 34 disposed in front of the load lock chamber 26a and supplying the same to the load lock chamber 26a.

Next, an operation procedure including a heat treatment step according to the present invention will be described.

First, in front of the door of the load lock chamber 26a, the cassette 34 on which the mirror wafer 55 is mounted is arranged. Next, the door of the load lock chamber 26a is opened, one mirror surface wafer 55 is extracted from the cassette 34 by the handler 35, and this mirror surface wafer 55 is removed from the load lock chamber 26a.
Is transferred onto the susceptor 28 in the quartz glass container 27 therein, and the door of the load lock chamber 26a is closed. At this time, the atmosphere outside the vapor phase growth apparatus 20 (the atmosphere containing moisture)
Flows into the load lock chamber 26a.

Next, the pressure inside the load lock chamber 26a is reduced. At the time of this pressure reduction, for example, the valve 32 → the valve 3
It is preferable to start the pump 22 and open the valve 24 after closing in the order of 3 → the valve 24. When the pressure in the load lock chamber 26a is sufficiently reduced (for example, to about several Torr), the valve 24 is first closed, and then the pump 22 is stopped. At this stage, the atmosphere outside the vapor phase growth apparatus 20 that has flowed into the load lock chamber 26a first has been almost completely exhausted from the load lock chamber 26a. Therefore,
In the reduced-pressure atmosphere in the load lock chamber 26a, there is substantially no moisture which becomes a problem in a vapor phase growth process performed later. However, at this stage, the CVD oxide film of the mirror-polished wafer 55 still contains moisture which is a problem in the vapor phase growth step, and the removal of this moisture will be performed later in the heat treatment step according to the present invention. Done.

When the decompression of the load lock chamber 26a is completed, nitrogen gas is introduced into the load lock chamber 26a to make the load lock chamber 26a normal pressure.
In this case, for example, by first opening the valve 32,
Start introduction of nitrogen gas into the load lock chamber 26a,
Eventually, when the pressure in the load lock chamber 26a becomes a normal pressure or a pressure slightly exceeding the normal pressure, the valve 33 is turned on.
Is opened, and the exhaust of the purge gas via the exhaust pipe 31 is started. When the load lock chamber 26a is under normal pressure, the valve 3
When the gas outlet 3 is opened, the atmospheric gas (possibly containing moisture) in the exhaust pipe 31 flows back into the load lock chamber 26a. It is possible to prevent the atmospheric gas in the exhaust pipe 31 from flowing back into the load lock chamber 26a. As described above, after the mirror wafer 55 is loaded into the load lock chamber 26a, the load lock chamber 26a is once depressurized, and thereafter, nitrogen gas is introduced into the load lock chamber 26a, and the atmosphere in the load lock chamber 26a is reduced. The replacement step of almost completely replacing the gas with dry nitrogen is completed. It should be noted that, even after the above operation is completed, nitrogen gas is continuously introduced into the load lock chamber 26a through the introduction pipe 30 (and exhausted through the exhaust pipe 31).

Next, a heat treatment step according to the present invention is performed. First, the halogen lamps 21,... Exemplifying the heating means are turned on, and the mirror surface wafer 55 on the susceptor 28 is set to 800 ° C.
The temperature in the load lock chamber 26a is increased until the temperature condition becomes less than 900 ° C. Specifically, the temperature condition here may be, for example, 800 ° C. When the temperature of the mirror wafer 55 is raised to 800 ° C., the output of the halogen lamps 21 is adjusted, and the temperature condition is maintained for a predetermined time (for example, 5 minutes or more and less than 30 minutes) to perform the heat treatment according to the present invention. Do.
By performing this heat treatment, water is desorbed from the CVD oxide film on the back surface side of the mirror wafer 55, and before the heat treatment is completed, the amount of water desorbed from the CVD oxide film is 0.1 pp.
m or less. As described above, a state in which the moisture which is a problem in the vapor phase growth step is sufficiently removed from the CVD oxide film of the mirror-finished wafer 55 is obtained. That is, as a result of the above-described replacement step and heat treatment step, there is substantially no moisture which is a problem in the vapor phase growth step, neither in the atmosphere in the load lock chamber 26a nor in the CVD oxide film of the mirror wafer 55. Becomes

After the above heat treatment step, the mirror wafer 55 is transferred from the load lock chamber 26a through the transfer chamber 3 to the reaction furnace 1a.
The procedure for carrying out the vapor phase growth step by transporting the epitaxial wafer 57 after the vapor phase growth step and the procedure for transporting the epitaxial wafer 57 after the vapor phase growth step from the reaction furnace 1a to the load lock chamber 6b via the transport chamber 3 solves the above problems. The procedure is the same as described in the section for performing

According to the vapor phase growth apparatus 20 of the first embodiment as described above, the heat treatment step according to the present invention can be performed in the load lock chamber 26a. Therefore, before the vapor phase growth, the moisture in the CVD oxide film of
CV can be reduced to a level that does not cause a problem during vapor phase growth.
Generation of moisture from the D oxide film can be substantially prevented. In addition, before performing the heat treatment process, the pressure in the load lock chamber 26a is once reduced in advance, and then the load lock chamber 26a is depressurized.
Is introduced into the load lock chamber 26a,
Since nitrogen can be almost completely replaced with nitrogen, the load lock chamber 26 can be removed from the outside of the vapor phase growth apparatus 20 (such as a clean room).
a and the transfer chamber 3 can be reduced as much as possible to bring moisture into the reaction furnace 1a. Therefore, since the vapor phase growth step is performed in a reaction gas atmosphere containing no water of interest, it is possible to suppress the formation of surface roughness on the surface of the epitaxial layer. The rate at which surface roughness is observed on the surface of the layer can be reduced. In addition, in an atmosphere that does not contain moisture,
Since 1 gas or silicon source gas can be supplied, the incidence of particles, stacking faults (SF), or metal contamination can be reduced.

In the first embodiment, the temperature for the heat treatment is increased after the nitrogen replacement in the load lock chamber 26a. For example, the temperature is increased immediately after the pressure is reduced. Alternatively, the heat treatment and a part of the nitrogen substitution may be performed in parallel.

[Second Embodiment] In a second embodiment, the heat treatment step according to the present invention is performed before the vapor phase growth step.
A case where the step is performed in a reactor for performing the vapor phase growth step will be described. In the second embodiment, since the same vapor growth apparatus (not shown) as the vapor growth apparatus 10 described in Means for Solving the Problems is used, the same components are denoted by the same reference numerals. And description thereof is omitted. Note that this second
The reaction chamber provided in the vapor phase growth apparatus used in the embodiment may be, for example, only one (single) reaction chamber 1a, but the number of reaction chambers may be two or more (plural). Good (for example, the reactor 1b may be provided) and optional.

In the second embodiment, in order to perform the heat treatment process according to the present invention, first, the mirror wafer 5
5 is loaded into the reaction furnace 1a and placed on the susceptor. Here, as shown in FIG. 12A, the internal temperature of the reactor 1a is maintained at about 800 ° C. even when the temperature is lowered (t0) after the vapor phase growth. Therefore, the mirror-faced wafer 55 starts heating at the same time as being loaded into the reaction furnace 1a (t1), and is immediately heated to 800 ° C. (t2).
When the temperature of the mirror wafer rises to 800 ° C., this state is maintained for 5 minutes or more and less than 30 minutes (until t3). Thereby, the heat treatment step according to the present invention is performed. When the heat treatment step is completed, t in FIG.
The process of changing the thermal environment in the reactor 1a is performed in the same temperature cycle as indicated by 12 → t13 → t14 → t15 → t16, and the process of supplying a predetermined raw material gas or the like in a timely manner in parallel with this process. Then, a vapor phase growth step is performed.

According to the second embodiment, the heat treatment step according to the present invention is performed in the reactor 1a for performing the vapor phase growth step, so that a special heat treatment furnace for the heat treatment step is not required. Further, according to the present embodiment, 1000 ° C. to 110 ° C.
Since the generation of moisture from the CVD oxide film in the temperature region of 0 ° C. can be suppressed, the rate at which surface roughness of the epitaxial layer is observed can be reduced.

In the second embodiment, the specular wafer 55 is kept at 800 ° C. for 5 minutes or more.
Although the example in which the heat treatment step is performed by holding for less than 0 minutes has been described, the present invention is not limited to this. Further, an example in which the heat treatment step is completed before the temperature of the reaction furnace 1a is started has been described. However, the present invention is not limited to this, and "the mirror wafer 55 is set to a temperature condition of 800 ° C. or more and less than 900 ° C. Time (that is, the time during which the heat treatment according to the present invention is performed) is 5 minutes or more and less than 30 minutes in total. " Therefore, for example, after the temperature is raised to a temperature near 900 ° C., the above-mentioned completion condition is satisfied by maintaining the temperature condition after the temperature raising for a predetermined time or by slowly raising the temperature to a temperature near 900 ° C. Processing may be performed.

[Third Embodiment] FIG. 13 is a conceptual plan view showing a vapor phase growth apparatus 50 used in the third embodiment. The third embodiment is characterized in that the heat treatment step according to the present invention is performed in a heat treatment furnace 51 connected to a reaction furnace 1b for performing a vapor phase growth step in an inert atmosphere (for example, a nitrogen atmosphere). And In order to preferably achieve this, the vapor phase growth apparatus 50 includes a heat treatment furnace 51 similar to the reaction furnace 1a. It is assumed that the inside of the heat treatment furnace 51 is always set to a predetermined temperature condition (for example, 800 ° C.) for performing the heat treatment step when the vapor phase growth apparatus 50 is started.

In order to perform the heat treatment process according to the present invention using the vapor phase growth apparatus 50, first, in the case of the vapor phase growth apparatus 10, as in the case where the mirror wafer 55 is carried into the reaction furnace 1a. Then, the mirror wafer 55 is carried into the heat treatment furnace 51, and the process directly proceeds to the heat treatment step. That is, as described above, the inside of the heat treatment furnace 51 is always, for example,
Since the temperature is set to 800 ° C., when the mirror-surface wafer 55 is carried into the heat treatment furnace 51, the temperature of the mirror-surface wafer immediately starts to rise, and immediately reaches 800 ° C. After the mirror wafer 55 reaches 800 ° C., the heat treatment step according to the present invention is completed by holding the wafer for a time of 5 minutes or more and less than 30 minutes. After this completion, the mirror-finished wafer 55 is carried out of the heat treatment furnace 51 to the transfer chamber 3 maintained in a nitrogen atmosphere as an inert gas.

On the other hand, in the reaction furnace 1 b, while the above-described heat treatment step is performed in the heat treatment furnace 51, vapor phase growth is performed on another mirror surface wafer 55. Accordingly, the mirror-finished wafer 55 carried out of the heat treatment furnace 51 after the heat treatment step has been subjected to the vapor phase growth in the reaction furnace 1b, and the epitaxial wafer 57 (having an epitaxial layer formed on the main surface of the mirror-finished wafer) is carried out. Until the epitaxial wafer 5
7 is carried out to the reaction furnace 1b after carrying out, and the vapor phase growth is similarly performed. During the vapor phase growth, similarly,
The next heat treatment step for the mirror wafer is performed in the heat treatment furnace 51.

The inside of the heat treatment furnace 51 is always kept in a hydrogen atmosphere. Therefore, the heat treatment process in the heat treatment furnace 51 is performed in a hydrogen atmosphere. In general,
The purified high-purity hydrogen gas has a lower concentration of contained impurities (which can be an unintended minute amount of dopant) than the high-purity nitrogen gas. Therefore, by performing the heat treatment process in a hydrogen atmosphere, the mirror-finished wafer 55 during the heat treatment process can be kept more clean, and as a result, the vapor phase growth after the heat treatment process can be performed under favorable conditions.

According to the third embodiment, the heat treatment is performed in the heat treatment furnace 51 connected to the reaction furnace 1b for performing the vapor phase growth step in an inert atmosphere. The vapor phase growth in the reaction furnace 1b can be performed under favorable conditions without exposing the mirror wafer 55 to the outside air.

In the third embodiment, the heat treatment step is performed in a hydrogen atmosphere. However, the present invention is not limited to this. For example, the heat treatment step may be performed in a nitrogen atmosphere.

Fourth Embodiment In a fourth embodiment, a case will be described in which the heat treatment step according to the present invention is performed following the step of growing a CVD oxide film. FIG. 14 shows the CV
FIG. 3 is a schematic front view showing an oxide film growth / heat treatment apparatus 60 for performing a heat treatment step according to the present invention following a D oxide film growth step. The oxide film growth / heat treatment apparatus 60 includes an oxide film growth portion 61 for growing a CVD oxide film on the main back surface of the chemical etch wafer and a substrate on which the CVD oxide film has been grown by the oxide film growth portion 61. On the other hand, a heat treatment section 62 for performing a heat treatment step according to the present invention is schematically configured. Of these, the oxide film growth part 61
Is for setting the substrate of the oxide film growth part 61 to the growth temperature of the CVD oxide film (for example, 350 ° C. to 450 ° C.)
A heating means 64 (for example, constituted by a halogen lamp or the like) is provided. Further, the heat treatment section 62 is constituted by a heating means 65 (for example, a halogen lamp or the like) for setting the substrate of the heat treatment section 62 to a predetermined temperature condition (800 ° C. or more and less than 900 ° C.) for performing the heat treatment step. ). Further, the oxide film growth / heat treatment apparatus 60 is, for example, a belt conveyor 63 for transferring a substrate from the oxide film growth section 61 to the heat treatment section 62.
And a handler for extracting substrates (chemically-etched wafers 66) one by one from the cassette 34 disposed upstream of the oxide film growth / heat treatment apparatus 60 and supplying the substrates to the belt conveyor 63. 35.

Next, a procedure for performing a CVD oxide film growth step using the oxide film growth / heat treatment apparatus 60 and subsequently performing a heat treatment step according to the present invention will be described.

First, the chemical etch wafers 66 are extracted one by one from the cassette 34 by the handler 35,
The wafers are sequentially transferred onto the belt conveyor 63 such that the main back surface of the chemical etch wafer 66 faces upward. At this time, in the oxide film growth part 61, the belt conveyor 6
A reaction gas obtained by mixing a source gas for growth with a carrier gas is supplied to the chemical etch wafer 3 above. Here, as the carrier gas, for example, an inert gas such as nitrogen is used, and as the source gas for growth, for example, 0.05% to 0.15% by volume of monosilane (S
A mixed gas of iH ₄ ) and 0.5% to 1.5% by volume of oxygen is used. Also, the CVD oxide film growth part 61
The growth temperature is set to 350 ° C. to 450 ° C. by the heating means 64. Therefore, the chemical etch wafer 66
While the CV is slowly conveyed on the belt conveyor 63 in the direction of arrow D, the CV containing 3% by weight or more of OH groups gradually appears on the main back surface of the chemical etch wafer 66.
A D oxide film is formed (a CVD oxide film growth step is performed).

The substrate 67 thus manufactured by forming the CVD oxide film on the main back surface of the chemical etch wafer 66 in the oxide film growth section 61 continues
It is conveyed on the belt conveyor 63 toward the heat treatment section 62. The temperature of the heat treatment section 62 is set to 800 ° C. or more and less than 900 ° C. by the heating means 65. Therefore,
In the heat treatment section 62, the belt conveyor 63
During transport toward the downstream side (direction of arrow E) by
The heat treatment step according to the present invention is performed on the substrate 67.
In the heat treatment unit 62, after the substrate 67 is heated to a temperature condition of 800 ° C. or more and less than 900 ° C., the substrate 67 is conveyed in the heat treatment unit 62 for 5 minutes or more and less than 30 minutes under this temperature condition. Heat treatment section 62 and belt conveyor 6
Of course, the dimensions of No. 3 and the conveying speed of the belt conveyor 63 are set.

According to the fourth embodiment, the heat treatment step according to the present invention can be performed continuously with the step of growing a CVD oxide film, thereby improving the productivity of the silicon single crystal substrate according to the present invention. I do.

[Fifth Embodiment] In a fifth embodiment, a heat treatment step according to the present invention is performed in a heat treatment furnace of a heat treatment apparatus between a CVD oxide film growth step and a vapor phase growth step. An example will be described.

FIG. 15 is a schematic front view for explaining a suitable example of the case where the heat treatment step is performed in the heat treatment furnace of the heat treatment apparatus between the CVD oxide film growth step and the vapor phase growth step. is there. A heat treatment device 83 shown in FIG.
A heating means such as a quartz glass container 87, a susceptor 88, a halogen lamp 81,..., And a gas supply pipe 85 for supplying an inert purge gas such as a nitrogen gas into the housing 83. And an exhaust pipe 86 for exhausting gas from the housing 83. Note that the inner region of the housing 84 constitutes the heat treatment furnace 83a.

In the present embodiment, for example, a CVD oxide film is formed after the CVD oxide film growth step by the CVD oxide film growth apparatus 70 for growing the CVD oxide film on the main back surface of the chemical etch wafer. Board
An example in which the wafer is transferred from the CVD oxide film growth apparatus 70 to the heat treatment apparatus 83 to perform the heat treatment step according to the present invention will be described.

The CVD oxide film growth apparatus 70 has the same oxide film growth section 6 as the oxide film growth / heat treatment apparatus 60 shown in FIG.
The belt conveyor 71 of the CVD oxide film growth apparatus 70 includes a chemical etch wafer 6 extending from the upstream side to the downstream side of the oxide film growth section 61 (in the direction of arrow F).
6 is conveyed.

In the space between the CVD oxide film growth apparatus 70 and the heat treatment apparatus 83, the substrate 67 transferred to the downstream side on the belt conveyor 71 of the CVD oxide film growth apparatus 70 is located.
Is mounted on the susceptor 88 of the heat treatment apparatus 83.

In the fifth embodiment, first, the CVD
Using the oxide film growth apparatus 70, a CVD oxide film growth step is performed, and C
The substrate 67 is manufactured by forming a VD oxide film. Next, the manufactured substrate 67 is transferred onto the susceptor 88 of the heat treatment apparatus 83 by the handler 72. Here, the inside of the heat treatment furnace 83 a of the heat treatment apparatus 83 is always set to a temperature condition of, for example, 800 ° C. or more and less than 900 by the halogen lamp 81. Therefore, the heat treatment furnace 83
As soon as the substrate 67 is carried into the area a, the temperature of the substrate 67 starts to rise and immediately reaches a temperature of 800 ° C. or more and less than 900 °. After reaching this temperature, the temperature is maintained for 5 minutes or more and less than 30 minutes to complete the heat treatment step according to the present invention. While the nitrogen gas is always introduced into the heat treatment furnace 83a through the gas supply pipe 85, the heat treatment furnace 8a
Since the atmospheric gas in 3a is constantly extruded and exhausted through the exhaust pipe 86, the CV of the substrate 67 during the heat treatment process is reduced.
Water desorbed from the D oxide film does not stay in the heat treatment furnace 83a. After the heat treatment process is completed, the substrate 67 is carried out of the heat treatment furnace 83a by the handler 72. Thereafter, a mirror polishing step or the like is performed, and the vapor phase growth step is performed in a predetermined procedure using, for example, the vapor phase growth apparatus 10 described above.

The present invention is not limited to the fifth embodiment. For example, after the step of growing a CVD oxide film, mirror polishing is performed by mechanochemical polishing to turn the substrate 67 into a mirror wafer. Alternatively, the heat treatment step according to the present invention may be performed in the heat treatment furnace 83a of the heat treatment apparatus 83.

[Sixth Embodiment] A sixth embodiment is directed to a chlorination step of performing a chlorination process on a silicon single crystal substrate having a CVD oxide film formed on the main back surface thereof; And a vapor phase growth step of forming a silicon epitaxial layer on the main surface of the semiconductor device.

In order to preferably accomplish this, the chlorination step is performed between the step of growing the CVD oxide film and the vapor phase growth step, preferably before the mirror polishing step. The chlorine treatment step is performed by introducing a chlorine (Cl ₂ ) gas into a container in which a silicon single crystal substrate having a CVD oxide film formed on the main back surface is placed. When chlorine gas acts on the CVD oxide film, OH groups contained in the CVD oxide film by 3% by weight or more are reformed by the oxidizing action of the chlorine gas. As a result, substantially no moisture is contained in the CVD oxide film, so that the concentration of moisture desorbed from the silicon single crystal substrate is set to 0.1 at a temperature of 800 ° C. or more and less than 900 ° C.
It can be 1 ppm or less.

[0076]

As described above, according to the structure of the present invention, the generation of moisture from the CVD oxide film can be prevented, so that the amount of moisture introduced into the reaction furnace can be greatly reduced. Further, by performing a heat treatment in advance at a temperature range of 800 ° C. or more and less than 900 ° C., generation of moisture from the CVD oxide film in a temperature range of 1000 ° C. to 1100 ° C. can be substantially prevented. Therefore, it is possible to suppress formation of an oxide film on the surface of the epitaxial layer, generation of particles in the reaction furnace, and generation of metal contamination during the vapor phase growth process.

[Brief description of the drawings]

FIG. 1 is a schematic plan view showing a single wafer type vapor phase growth apparatus.

[Fig. 2] Opening the door of the load lock room and opening the load lock room to a clean room atmosphere of room temperature 25 ° C and humidity 46%.
It is a figure which shows a mode that the water concentration in a load lock room decreases with time progress after closing the door of a load lock room after exposing for 0 minute.

FIG. 3 is a diagram showing an amount of moisture brought into a transfer chamber from a load lock chamber.

FIG. 4 is a diagram showing an amount of moisture brought into a reaction furnace from a load lock chamber via a transfer chamber (when a mirror-surface wafer is not transferred).

FIG. 5 is a diagram showing the amount of moisture brought into a reaction furnace from a load lock chamber via a transfer chamber (when a mirror-surface wafer having no CVD oxide film formed on the main back surface is transferred).

FIG. 6 is a diagram showing the amount of moisture brought into a reaction furnace from a load lock chamber via a transfer chamber (in the case where a mirror-surface wafer having a CVD oxide film formed on the main back surface is transferred).

FIG. 7 is an enlarged view showing one of a plurality of epitaxial growth steps shown in FIG. 6;

FIG. 8 is a diagram showing a water concentration generated when a mirror-surface wafer having a CVD oxide film formed on a main back surface is heated in a hydrogen atmosphere.

FIG. 9 is a diagram showing the concentration of moisture generated in each temperature region when a mirror-surface wafer having a CVD oxide film formed on a main back surface is heated in a hydrogen atmosphere.

FIG. 10 is a diagram showing a haze level observed by irradiating an epitaxial layer having a rough surface with light for each epitaxial wafer.

FIG. 11 is a schematic side sectional view showing a load lock chamber for performing a heat treatment step according to the present invention.

FIG. 12 is a diagram showing an example of a temperature cycle when a heat treatment step according to the present invention is performed in a reactor for performing the vapor phase growth step before the vapor phase growth step.

FIG. 13 is a schematic plan view showing a vapor phase growth apparatus for performing a processing step according to the present invention in a heat treatment furnace connected in an inert atmosphere to a reaction furnace for performing a vapor phase growth step. .

FIG. 14 shows a heat treatment step according to the present invention,
FIG. 5 is a schematic front view showing an apparatus for performing the step following the step of growing a CVD oxide film.

FIG. 15 is a schematic front view showing equipment for performing a heat treatment step according to the present invention in a heat treatment furnace of a heat treatment apparatus between a CVD oxide film growth step and a vapor phase growth step.

[Explanation of symbols]

 26a Load lock chamber 1a, 1b Reactor 51 Heat treatment furnace 83 Heat treatment device 84 Heat treatment furnace

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5F045 AA03 AA06 AB02 AB32 AC01 AC13 AD14 BB12 BB14 EB08 EB09 EB12 EB15 EK11 GB04 HA06 HA16

Claims (12)

[Claims] 1. A silicon single crystal substrate having a CVD oxide film on a main back surface, which is subjected to a heat treatment at a temperature condition of 800 ° C. or more and less than 900 ° C. so that the concentration of water desorbed under said temperature condition is 0.1 ppm. A silicon single crystal substrate characterized by the following. 2. A silicon single crystal substrate having a CVD oxide film formed on its main back surface is subjected to a heat treatment at a temperature of 800 ° C. or more and less than 900 ° C., so that the silicon single crystal substrate is desorbed from the silicon single crystal substrate under the above temperature conditions. 0.1 ppm water concentration
A method for manufacturing a silicon epitaxial wafer, comprising: performing a heat treatment step described below and a vapor phase growth step of forming a silicon epitaxial layer on the main surface of the silicon single crystal substrate by vapor phase growth in this order. 3. The time for performing the heat treatment is 5 minutes or more.
3. The method for producing a silicon epitaxial wafer according to claim 2, wherein the time is less than 0 minutes. 4. The method for manufacturing a silicon epitaxial wafer according to claim 2, wherein the heat treatment step is performed in a load lock chamber in a nitrogen atmosphere. 5. The method for manufacturing a silicon epitaxial wafer according to claim 4, wherein when the silicon single crystal substrate is put into the load lock chamber, the pressure is once reduced, and then nitrogen gas is introduced. 6. The silicon epitaxial wafer according to claim 2, wherein the heat treatment step is performed in a heat treatment furnace connected to an inert atmosphere with a reaction furnace for performing the vapor phase growth step. Production method. 7. The method for manufacturing a silicon epitaxial wafer according to claim 2, wherein the heat treatment step is performed after the step of growing a CVD oxide film. 8. The silicon epitaxial wafer according to claim 2, wherein the heat treatment step is performed in a heat treatment furnace of a heat treatment apparatus between a CVD oxide film growth step and the vapor phase growth step. Manufacturing method. 9. The silicon epitaxial wafer according to claim 2, wherein the heat treatment step is performed in a reactor for performing the vapor phase growth step before the vapor phase growth step. Method. 10. A chlorination process for chlorinating a silicon single crystal substrate having a CVD oxide film formed on a main back surface, and a vapor phase growth for forming a silicon epitaxial layer on the main surface of the silicon single crystal substrate. And a step of performing the steps in this order. 11. The silicon according to claim 10, wherein the concentration of water desorbed from the silicon single crystal substrate is set to 0.1 ppm or less under a temperature condition of 800 ° C. or more and less than 900 ° C. by the chlorination process. Manufacturing method of epitaxial wafer. 12. The method for manufacturing a silicon epitaxial wafer according to claim 10, wherein the chlorination step is performed between the step of growing the CVD oxide film and the step of vapor phase growth.